Mercury arc rectifier



March 1, 1932. A. SIEMENS. 7 1,847,141.

MERCURY ARC RECTIFIER Filed July 2, 1930 INVENTOR AV/red .5/mens.

- ATT.ORNEY Patented Mar. 1, 1932 UNITED STATES PATENT OFFICE ALFRED SIEMEN S, OF BERLIN-CHARLOTTENBURG, GERMANY, ASSIGNOR T0 WEST- INGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VAN IA MERCURY ARC RECTIFIER Application filed July 2, 1930, Serial No. 465,380, and in Germany July 4, 1929.

My invention relates to mercury-arc rectifiers and particularly to electrodes for such rectifiers.

Prior to my invention, it was common practice to provide annular mercury-filled cathodes for use in mercury-arc rectifiers.

It is an object of my invention to provide an improved electrode for mercury-arc rec tifiers.

It is a further object of my invention to provide a starting anode in proximity to the surface of the mercury cathode.

Other objects and advantages of my invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which Figure 1 is a partial sectional elevation of a rectifier embodying my invention, and

Fig. 2 is a similar view of a modification. The apparatus disclosed in the drawings comprises a tank 1, preferably of metal, having a bottom opening 2. The cathode proper consists of an annular dish-like receptacle 3 adapted to receive the cathode mercury 4.

The dish-like receptacle 3is insulated from the main tank 1 of the rectifier by an annular insulator 5. v A

In the center of the cathode dish '3 is an upstanding island, which may be a flat ringlike base 6 surmounted by an insulated top 7 as shown in Fig. 1, or it maybea cone 19 as shown in Fig. 2. Y

In the embodiment shown in Fig. 1, the top 7 is insulated from the base 6 by-a ring or other suitable insulator 8. .The top 7 is preferably made hollow so that it may be cooled to provide a condensing surface for mercury vapor rising from the cathode mercury 4. Any suitable-cooling fluid such as oil or water may be circulated to the island .top 7 by pipes 9. When Water is used as the cooling medium, it is necessary to provide suitable rubber hose connections. for insulating the island top from the circulating system of the remainder of the rectifier. However, when oil or other insulating fluid is utilized as a cooling medium only an insulating washer (not shown) is necessary to insulate the island top from the remainder of the tank.

A cathode screenlO is attached to the top 7 in sucha manner that itwill deflect a portion of the rising mercury vapor against the cooled surfaceof the island.

The insulated island top 7, with its appended screen 10, serves the additional purpose of a starting anode. 'A starting potential is applied to the island 7 by means of a conductor 15 directly connected thereto. The proximity of the screen 10 to the surface of the cathode mercury 4vpermits the striking of the starting are by applying potential directly to the island 7. A keep-alive arc may be maintained in the same manner.

In the modification shown in Fig. 2, the island 19 is a conical projection formed integral with the material of the cathode dish 3, and is uninsulated therefrom. The island 19 is cooled as a part of the cathode dish by means of pipes 20 and 21. The cold water, or other cooling fluid, is admitted through the pipe 20 so that the upper surface of the island 19 is strongly cooled and acts as a condensation surface. A screen 25, separated a short distance from the island 19, serves as a baflie to direct mercury vapor from the cathode 4 against the cold condensation surface of the island 19, in the same manner that the screen 10 directs mercury vapor against the island 7.

The screen 25 is supported above the island 19 by suitable insulators 26. The insulated screen is separated from the mercury 4 by a small distance, in the same manner as the screen 10 is separated from the mercury, and starting potential is applied to the screen by the conductor 15, which is insulated from the cathode dish 3 by vacuum-proof insuwithout departing from the spirit and scope of my invention, as defined in the appended claims.

I claim as my invention:

1. A compound electrode for a mercury-arc rectifier comprising a' cathode body, a mercury-cathode pool therein, means for insulating said cathode body from the rectifier tank, an island in said cathode body, a starting anode above said island, means for insulating said anode from said cathode body, and means for supplying a starting potential to said anode.

2. An electrode for a mercury-arc rectifier comprising an annular cathode body, a mercury cathode in said cathode body, an island in said cathode, means for cooling said island and means for conducting mercury vapor from said cathode against the surface of said island, a starting anode for said rectifier comprising a screen located above the cathode and insulated therefrom, said screen being in proximity to said cathode, and means for supplyin a starting current to said'screen.

'3. cathode for a mercury-arc rectifier comprising a rectifier tank, an annular cathode container, means for insulating said container from said tank, a mercury-cathode pool in said container, an island in said container, a screen above said island, and means for applying a starting potential to said screen.

4. A cathode for a mercury-arc rectifier comprising a rectifier tank, an annular cathode container, means for insulating said container from said tank, a mercury-cathode pool in said container, an island in said container, a screen located above said island means for insulating said screen from sai cathode, and means for condensing mercury vapor between said island and said screen.

5. A cathode for a mercury-arc rectifier comprising a rectifier tank, an annular cathode container, means for insulating said container from said tank, a mercury-cathode pool in said container, an island in said container, a screen located above said island, means for insulating said screen from said cathode, and means for condensing mercury vapor between said island and said screen,

and means for supplying a starting potential c to said screen.

6. An electrode for a mercury-arc rectifier comprising a metal rectifier tank having an opening therein, a mercury container below said 0 ening, means for insulating said container rom said tank, a mercury pool in said container, an island in said mercury and means for cooling said island, a screen located above said island and insulated from said mercury.

In testimony whereof, I have hereunto subscribed my name this 13th day of June, 1930.

' ALFRED SIEMENS. 

